Loud-speaker motor



June 25, 1929. [)5 FOREST 1,718,337

LOUD SPEAKER MOTOR Filed Oct. 24, 1925 j g H.

. INVENT R.

v CD a BY r y 1 v A A TTORNEYS.

Patented June 25,1929.

UNITED STATES PATENT OFFICE.

LEE DE FOREST, 0]? NEW YORK, N. Y., ASSIGNOR TO UTAH RADIO PRODUCTS "COM- PANY, INCORPORATED, OF SALT LAKE CITY, UTAH, A CORPORATION OF UTAH.

LOUD-SPEAKER MOTOR.

Application filed October 24, 1925. Serial No. 64,596.

This invention relates in general to loud speaker motors or units of the balanced armature type, for use in vibrating the diaphragm of sound reproducing devices. More partic of such devices. Itis the purpose of my in-.

.vention to producean instrument which is simple to construct, eflieient in operation and easily maintained in proper working condition. Specifically the purpose of my invention is to provide a simple supporting member for the armature of the device. The invention resides in the construction, arrangement and relative location of parts, as will be more fully described hereinafter and shown in the drawings, in which I have shown one embodiment of my invention.

Referring to the drawings, in which the same reference numerals will be used to indicate the same parts throughout the several views,

Fig. 1 is a top plan view of a loud speaker unit.

Fig. 2 is a bottom plan view of the same device with some of the parts broken away.

Fig. 3 is an end elevational view of the device.

Fig. 4 is a cross-sectional view taken on the line 44, Fig. 1, looking in the direction of the arrows.

Fig. 5 is a view partly in section taken on the line 55 of Fig. 1, and partly in elevation. s

Fig. 6 is a cross-sectional view through the pole pieces showing the armature mounting.

Fig. 7 is a plan view of the armature mount- Iteferring to Fig. 1, reference numeral 1 indicates a permanent magnet of the wellknown horse-shoe type. Attached transversely across the poles of the magnet 1 are two pole pieces or shoes 2, upon which is mounted cap piece 3. The pole pieces and cap piece are rigidly secured to the poles of the magnet by means of bolts 4. The cap 3 is provided with a. projection 5 on which is se 1 cured an anchor casting 6 by means of a threaded bolt. This anchor casting when mounted on theprojection 5 of the cap piece 3 forms a U-shaped support across the open end of which extends a two-piece resilient reed 7, 7. Fulcrumed between the two resilient reed members 7, 7 is the armature 8 which extends between the pole pieces 2. Attached atone end of the armature 8 is a non-magnetic rod 9, which is secured at its free end to a nonmagnetic spring member 10 upon which is secured a short arm 11. The spring member 10 is rigidly attached by means of a bolt to the pole piece. Mounted within the pole piece 2 surrounding the armature 8 are two solenoids, 12, 12 which are electrically connected in series by a lead 13, and the free ends of which terminate in connecting leads 14 and 15.

A particularly novel feature of my invention consists of the method of mounting the armature on the cap 3. I have provided a simple single casting of non magnetic material 6, which is easily attached to the cap 3 so that in case it is necessary to remove the coils or the armature from the motor unit, it is only necessary to remove one screw and ac cess may then be had to the interior of the device.

It will be seen, therefore, that by my invention, I have produced a novel and valuable modification in balanced armature type loud speaker units which serves to simplify their construction and maintenance.

Having now pointed out my invention, what I seek to secure by United States Letters Patent is 2.

1. In a loud speaker unit, a permanent magnet, transverse pole pieces on said magnet, a cap extending along and secured to the corresponding faces of said pole pieces and spanning the gap therebetween, an armature mounted between said pole pieces, a support mounted on said cap, and a reed mounted on said support and serving as a fulcrum for said armature.

2. In a loud speaker unit, a permanent magnet, transverse pole pieces on said magnet, a cap extending along and secured to the corresponding faces of said pole pieces and spanning the gap therebetween, an armature mounted betweensaid pole pieces, a nonmagnetic support mounted on said cap extending transversely of it, a resilient reed on said support in which said armature is mounted.

3. In a loud speaker unit, a permanent magnet, transverse pole pieces on said magnet, a cap extending along and secured to the corresponding faces of said pole pieces and spanning the gap therebetween, an armature mounted between said pole pieces, a

transverse support on said cap, a resilient two piece reed mounted on said support and coils encircling said armature.

4. In a balanced armature motor for sound reproducing devices, the combination of a magnet, pole shoes and cap mounted on said magnet and pole shoes, an armature pivoted between said pole shoes, an anchor casting mounted on said cap, said cap and anchor casting forming a U-shaped support, and a reed mounted across the open end of the U- shaped support forming a support for said armature.

5. In a balanced armature motor for sound reproducing devices, the combination of a magnet, pole shoes and cap mounted on said magnet and pole shoes, an armature pivoted between said pole shoes, an anchor casting mounted on said cap, said cap and anchor castmg forming a U-shaped support, a i'AVO'PlGCB resilient reed mounted across the open end of and on said U-shaped support and forming a resilient fulcrum for said armature. v

. 6. In a balanced armature motor for sound reproducing devices, a horseshoe type per-' 30 posite the gap between said pole pieces, an L shaped anchor member secured to said projection and extending therefrom across said pole pieces in a direction transverse of said cap, said projection and a leg of said anchor member providing oppositely positioned supbridging the gap-therebetween, a cap resting 45 upon said pole shoes, means to secure the magnet, pole shoes and cap together, a projection upon said cap opposite the gap between said pole shoes, an L-shaped anchor member secured to said projection by readily detachable means, and extending therefrom across said pole pieces in a direction transverse of said cap, said projection and a leg of said anchor member providing at their ends supporting surfaces, a reed supported on said surfaces, and an armature fulcrumed on said reed.

In testimony whereof I have hereunto set my hand on this 19th day of October, A. I).

LEE 1m FOREST. 

